This is a multicenter, phase I randomized double-blind placebo controlled study to determine the safety, pharmacokinetics and pharmacodynamics of recombinant human D Nase 1 (rhDNase) in patients with systemic lupus erythematosus (SLE). The safety & tolerance of a single intravenous (IV) administration of rhDNase & multiple subcutaneous (SC) and IV doses of rhDNase will be determined. The pharmacokinetics of rhDNase after IV and SC administration will be characterized in patiens with SLE.